Truing device for abrasive wheels



May 29, 1934. G J U ON 1,960,760

TRUING DEVICE FOR ABRASIVE WHEELS Filed April 9, 1928 3 Sheets-Sheet lMay 29, 1934. G, J. SUTTON TRUING DEVICE FOR ABRASIVE WHEELS Filed April9. 1928 3 Sheets-Sheet 2 May 29, 1934. G J SUTTON THUING' DEVICE FORABRASIVE WHEELS 5 Sheets-Sheet 3 Filed April 9. 1928 l... v H56ATTOR/Vf) Patented May 29, 1934 UNITED STATES TRUING DEVICE FOR ABRASIVEWHEELS Gerald John Sutton,

Westminster, London,

England, assignor to Percy Nuckey and Robert John Scott, both of London,England Application April 9, 1928, Serial No. 268,684 In Great BritainApril 21, 1927 I 13 Claims.

This invention relates to a machine for use in forming, shaping, truingand reconditioning ob- .jects for example grinding wheels or grindingdiscs and other objects, the said machine being of the kind in which anabrading tool such as a diamond is carried by a pantographic appliancewhich is actuated in such manner as to cause the diamond to act on asurface when in rotation so as to true the said surface.

The general object of the present invention is to provide an improvedmachine of the aforesaid kind which is simple in operation, eilicientand permits of the work being trued in one operation and by unskilledlabor without removal of the work or reversal of the device as well asallowing of the finished size of the work being read at a glance,however much the object such as the grinding wheel or grinding disc hasbeen reduced in the truing operation.

A further object of the invention is to provide means whereby theabrading tool such as a diamond carried by the pantographic device canbe rectilineally displaced towards or from r the grinding wheel or discor the object to be trued.

A further object of the invention is to provide means whereby a masterpattern which coacts with a stylus carried by the pantographic appliancecan be rectilineally displaced in a direction to vary the depth of cutindependently of the movement of the pantographic device.

Another object of the invention is to provide means whereby the finishedsize of the article on which the grinding wheel or grinding disc is toact, can be read at a glance so that the operator definitely knows thatthe grinding operation of the screw-threaded or otherwise formed articleis complete.

These and other objects will become apparent from the detaileddescription hereinafter contained.

In order that the invention may be clearly understood and readilycarried into efiect, reference is made to the accompanying drawingswhich show diagrammatically and by way of example -a forming, shapingtruing and/or reconditioning device in accordance with the presentinvention.

Fig. 1 is a plan of a machine constructed in accordance with the presentinvention.

Fig. 2 is a side elevation of Fig. 1.

Fig'Tfi is an end elevation of Fig. 1 with the head stock removed andthe base of the machine shown in section and looking in the direction ofthe arrows 3-3 Fig. 1.

Fig. 4 is a detailed plan view on an enlarged scale of the pantographicappliance and the diamond holder carried thereby.

Fig. 5 is an end view of the construction shown in Fig. 4.

Figure 6 is a diagrammatic view of the pantograph mechanism.

Referring to the drawings, 1 denotes a cutting or abrading tool of anysuitable type which in the illustrated embodiment comprises, forexample, a diamond of non-circular profile, for instance it may beshaped so as to conform to the natural cleavage lines 'of the stone. Theprofile of the former or stylus 14, hereinafter more fully described, ismade so as to be identical with the profile of the abrading tool but thelatter is, of course, on a smaller scale than said stylus. 2 indicatesgenerally a pantographic appliance and 3 is a master pattern or former,4 being a precision gauge and 5 an abrading wheel or grinding wheel ordisc. In the constructional example illustrated a simple form of wheelhas been chosen and therefore a simple form of master pattern or formerfor the sake of simplicity, but more complicated forms can be dealt withor treated with the apparatus of the present invention.

The pantographic appliance 2 which is fixed at or is adjustable to thedesired ratio conveniently comprises an arm 6 which is convenientlyconnected as at 7, to a slide 8 mounted on a cross slide 9 relatively towhich the slide 8 may be adjusted by a screw 10. To the arm 6 of thepantographic appliance is pivoted as at 11 near its pivoted end a shortarm which is represented by the distance between the pivot 11 and theoperative face of the diamond 1 or other tool as indicated by the dottedline 1a in Fig. 4, and to the arm 6 at or near its outer end as at 12 ispivoted a long arm 13 which carries a tracer or feeler 14. Thepantographic appliance 2 comprises a parallel arrangement of linksnamely 6, '15, 16 and 17, these links being pivotally interconnected atthe points 11, 18, 19 and 12. The link 16 carrying the blocks 16 inwhich the diamond 1 is supported and the arm 13 carrying the tracer orfeeler 1% together with the rods or links forming the pantographicappliance are angularly displaceable on the pivotal support 7. Themaster pattern 3 is mounted on a slide 20 which can be displaced atright angles to the slide 9. Displacement of the slide 20 in a directionparallel to the plane of the grinding wheel or disc 5 can be effected bymeans of the hand wheel 21 on the screw 21' the era master pattern 3being secured to the slide 20 by bolts 22 or other suitable means.

Figure 6 is purely a diagrammatic view of the pantograph mechanism,while Figure 4 shows more particularly the diamond holder and the meansfor setting the latter in correct position. In the diagrammatic viewshown in Figure 6, the arm A-C is pivoted to the slide 8 at A. At apoint B such that A-C equals four times A-B, a short arm EB and at C along arm F--C are pivoted to the arm A-C, the length of FC being fourtimes the length of E-'-B.

EB is extended at B and FC is extended to C, EB and 0-0 being of equallength and the points B'C' are pivotally linked together. The actualparts corresponding to F-C and C-C' are 13 and 1'7 (Figures 1,and 4) andthese are in one piece. The function of the link coupling the rearwardextension of the two arms is to maintain the latter parallel to eachother throughout their movement. These linked extensions are shown indotted lines so that the parts governing the ratio of the pantograph maybe more clearly visualized. (In practice the arm A--C is duplicated forthe sake of rigidity).

A diamond is rigidly mounted on EB and a stylus shaped to conform to theprofile of the diamond is mounted rigidly on F-.-C.

Any suitable point such as F on the outward face of the stylus, forinstance on the center line indicated by the line 13' Figure 6 being setat a known distance from C, the corresponding central point E on theoutward face of the diamond must be set at a distance from B so that theratio of EB to F-C is the same as the ratio of A-B to A-C and the lineEB must be parallel to the line F--C.

To complete the diagram, a former is indicated at 3 and the profile ofthe grinding wheel under treatment is shown at 5 (H). The angulardisplacement of the stylus during movement over the former and theexactly corresponding displacement of the diamond on a reduced scale areshown by the view of the mechanism in another position indicated in dotand dash lines.

It will be seen that so long as the radius at the corners of theselected diamond is not greater than the radius R at the foot of thethread form a diamond of very substantial proportions may be used totrue wheels for the grinding of very fine thread forms.

It will be clear from the diagrammatic rep resentation that the shortarm EB and the long arm FC represent distances from the pivots B and Cto points on the operative face of the diamond and stylus whichcorrespond in position and that to, obtain the results required thelines joining these points respectively must be parallel to each otherand of correct ratio in length. (It should be noted that in theconstruction shown in the drawings, the lines joining these criticalpoints are parallel to one another and of the required ratio in length,although the parts carrying the diamond and stylus do not follow thestraight lines indicated in the diagram for reasons of constructionalconvenience l When a new diamond is to be mounted, the appropriatestylus, (made to a corresponding profile as stated), is mounted on thelong arm of the pantograph and the effective length and angular positionof the arm F-C as above defined are found. The diamond must then be somounted that the efi'ective length of the theoretical arm EB is ofcorrect ratio with, and parallel to,

For this purpose, in practice the diamond is mounted in a frame or blockrigidly held to the link 16 and this block is provided with means ofadjusting the position of the diamond so that its operative face may bebrought into such a position that its distance and position relativelyto the pivot 11 fulfill the conditions stated above.

The grinding wheel or disc 5 is mounted and rotatable in a suitablesupport 23 which is carried by the slide 9. In the example illustratedthe grinding wheel or disc 5 has a simple operative face or profilewhich consists of a single ridge or rib 24 and the master pattern orformer 3 is of the same shape as the profile of the grinding wheel ordisc but of much larger dimensions.

The ratio between the profile of the wheel or disc 5 and that of themaster pattern 3 depends on the ratio of reduction or enlargement ofmovement which it is desired to produce by the pantographic applianceand such ratio can be varied to meet requirements. In the constructionalform illustrated by way of example the ratio of the distance of thefulcrums 7 and 11 to the pivotal points 7 and 12 is as 1 to 25. Likewisethe ratio of the distance between the point 11 and the point of thediamond 1 to the distance between the point 12 and the point of contactof the tracer or feeler 14 with the master pattern 3 is as 1 to 25. Theaforesaid ratio has been found a convenient one to allow of a speedyoperation and also to secure a high degree of accuracy.

Mounted on suitable guides on the slidable frame 9 is a subsidiary slide25 which carries the precision gauge 4. The precision gauge 4 whichaffords a visible reading of the adjustment of the cutter or abradingtool 1 may be of any suitable construction but in the present form itcomprises a circular scale graduated in thousandths of an inch overwhich a pointer 26 or index hand is adapted to move the said index handbeing operated by a spring controlled stem 27. The outer end of the stem2'7 bears against an adjustable screw stop 28 mounted in a fixed orstationary bearing 29 secured to a longitudinally displaceable slide 30on which the slide 9 carrying the slide 8, the slide 20, and the gaugeslide 25 are mounted. The slides 20, 25 and the gauge slide guides 31,32 are displaceable crosswise with the slide 9.

The gauge slide 25 is actuated by the slide 20 through a lever 33pivotally connected as at 34 to the slide 20 and fulcrumed at 35 in thegauge slide guide 32 the other end of the lever being pivotallyconnected as at 36 to the gauge slide. The arms of the lever 33 arearranged to produce or reproduce movements in accordance with the ratiosof the movements of the pantographic appliance. In the presentconstructional form shown by way of example the ratio of the distancebetween the points 36 and 35 to the distance between the points 35 and34 is as 1 to 25. The work piece is shown at 37 and is mounted betweenthe usual centres of support 38, 39. The cross slide 9 which carries thegrinding wheel and its support 23 and the adjustable slides 8 and 20 forthe pantographic appliance 2 and the master pattern 3 respectively aswell as the gauge slide guides 31, 32 with the gauge slide 25 can beadjusted relatively to the work piece 37 by means of a hand wheel 40 andscrew 40.

The shape of the operative face of the tracer or feeler 14 is the sameas that of the abrading tool or diamond 1 but obviously in the exampleshown it is of considerably larger dimensions and proportions accordingto the ratio required.

The apparatus operates as follows: A finished work piece for example ascrew threaded tap or master tap may be mounted between the centres 38and 39. The cross slide 9 is then adjusted so as to bring the ridge 24into the bottom of the recess between two adjacent threads on the workpiece 37. The pointer or index hand 26 is then adjusted to zero.Hitherto the pantographic appliance has been swung to one side by movingthe arm 13 to the right which takes the diamond 1 or cutter clear of thegrinding wheel or disc 5.

The screw threaded work piece 3'7 for example the master tap is thenremoved and the desired work piece is substituted therefor. The grindingdisc or wheel 5 is then displaced by displacement of the slide 30 to thebeginning of the work piece or vice versa and the grinding wheel or disc5 is adjusted to the correct position and then set in rotation by meansof the pulley 41 connected by a belt (not shown) or other suitable meansto a rotatable piece of mechanism, or line of shafting. The work piecemay be caused to travel during its rotation to give the required helicalor thread form or the grinding wheel or disc may be carried by the slideor saddle 30 past the work piece. This operation is repeated until suchtime as it is considered that the grinding wheel or disc requiresreconditioning or truing. When such occasion arises the slide 20 andwith it the master pattern 3 are displaced outwardly by rotation of thescrew 21' a definite or suitable amount. This has the eifect of bringingthe diamond l, cutter or abrading tool up to the grinding wheel 5 andthe diamond is then caused to move across or over the edge of thegrinding wheel whilst the latter is in rotation by moving the ieeler 14over and in contact with the master pattern 3. Such an operation renewsthe edge of the grinding disc or wheel 5 so that the latter is againready for further use. In the adjustment of the slide 20 the diamondwill have been displaced inwardly a definite but unknown amount. Thegrinding wheel 5 is again brought into contact with the work piece 37and the aforesaid cycles of operation are renewed until the grinding orabrading wheel 5 has cut into the work pieceto such an extent that thepointer 26 or index hand indicates zero. In this position the form orshape cut on the work piece 37 will correspond exactly with the form orshape on the master tap or work piece to which the grinding wheel hasbeen previously set. It should be understood however that when the slide20 is displaced definitely an unknown amount the gauge slide 25 has beenforced inwardly precisely the same amount as the diamond l or cuttingtool. The distance the gauge slide has been forced inwardly will beindicated by the index hand or pointer 26, and until this index hand orpointer 26 returns to zero then the cutting action on the work piece 3'?will require to be continued and the shaping, forming, truing and thereconditioning oi the edge of the grinding disc or wheel 5 will notaifect the reading of the gauge 4. Forming, shaping, truing and/orreconditioning or the grinding wheel or disc need only be effected whendesired or only when considered necessary. In any case the cuttingaction on the work piece 37 by the grinding wheel or disc 5 should ifnecessary or required be continued until the ridge 24 has penetrated thework piece 37 to such an extent that the index hand 26 on the gaugeindicates zero.

The invention has hereinbefore been described as applied to a grindingwheel or disc of simple contour but it should be clearly understood thatwheels or other articles having more complicated operative surfaces orcontours may be treated by the apparatus of the present invention, andfur--- ther although the invention has been described above as appliedto the shaping of a grinding wheel having a contour which is formed,shaped, trued or reconditioned after use the apparatus of the presentinvention may be applied to the production or formation of any desiredcontour or the reconditioning of a formed contour or face upon a wheel,disc, rod cylinder, hollow cylindrical body or other articles during therotation of such articles.

What I claim is:-

1. In a machine of the class described, the combination of a grindingwheel adjustable in opposite directions in its own plane, a pantographicappliance pivotally supported adjacent to the grinding wheel, anabrading tool carried by the pantograph, a stylus having anapproximately similar profile to that of the abrading tool and carriedby one arm of the pantographic appliance, a master pattern associatedwith the said stylus, a slide carrying the master pattern, a subsidiaryslide, a gauge and means fulcrumed in a relatively stationary part ofthe machine and coupling the subsidiary slide to the master patternslide to effect displacement of the subsidiary slide in a directionopposite to that of the master pattern carrying slide so as to effectthe adjustment of the gauge reading to suit the reduced diameter of thegrinding disk.

2. In a machine of the class described, the combination of a grindingwheel, a pant'ograph pivotally supported and rectilineally displaceablein opposite directions relatively to the grinding wheel, an abradingtool carried by the pantograph, a stylus arm forming an arm of thepantograph and having a stylus adapted to engage a master pattern, agauge mounted on an adjustable slide, an adjustable slide carrying themaster pattern and a lever coupling the master pattern slide with thegauge slide.

3. In a machine of the class described, the combination of a grindingdisk, a pantograph, an abrading tool mounted thereon, a stylus, a masterpattern mounted on an adjustable slide and with which the stylus coacts,a precision gauge mounted on an adjustable slide, and a lever connectingthe gauge slide and the master pattern slide and pivotally fulcrumed toa relatively stationary part of the machine so that the said bartransmits the movement ofthe master pattern slide to the gauge slide,the movement of the latter being less in extent by the same ratio asthat adopted for the pantograph mechanism.

4. In a machine of the class described a device for re-conditioning theoperative face of a grinding element comprising in combination a mainsupporting frame, a tool holder, an abrading tool of non-circularoperative profile rigidly mounted in said holder a pantograph linkagemechanism pivotally mounted on said frame and rigidly carrying said toolholder on one of said links, a stylus rigidly mounted on another link ofsaid pantograph and having an operative face corresponding in profile tothe operative face of the abrading tool but on a larger scale and amaster pattern mounted on said frame and located adjacent said stylus,the linkage of the pantograph being such that movement of said stylus incontact with the pattern causes successive operative points of theprofile of said abrading tool contacting with the element to correspondin position in respect of said element to similar successive operativepoints of the profile of said stylus in respect to said pattern.

5. In a machine of the class described a device for reconditioning theoperative face of a grinding element comprising in combination a mainsupporting frame, a tool holder, an abrading tool rigidly mounted insaid holder and having a noncircular operating face, a stylus having anoperative face corresponding in profile to the operative face of saidabrading tool but on a larger scale, a master pattern mounted on saidframe and adapted to co-act with said stylus and a pantograph linkagemechanism pivotally mounted on said supporting frame having said toolholder rigidly mounted on one link and said stylus mounted on a longerlink, the arrangement of said pantograph, said tool, and said stylusbeing such that corresponding parts of the operative profiles of saidtool and said stylus will always be maintained in parallel relationshipon movement of said stylus over said pattern.

6. In a machine of the class described a device for reconditioning theoperative face of a grinding element comprising in combination a mainsupporting frame, a tool holder, a diamond abrading tool having anoperative face of irregular contour rigidly mounted in said holder, astylus having an operative face corresponding in profile to theoperative face of said abrading tool but on a larger scale, a masterpattern mounted on saidv frame and adapted to co-act with said stylus,and a pantograph linkage mechanism pivotally mounted on said supportingframe having said tool holder rigidly mounted on one link and saidstylus rigidlymounted on a parallel link, the ratio between the sizes ofthe operative faces of said tool and said stylus being the same as theratio between the lengths of said parallel links.

'I. In a machine of the class described a device for re-conditioning theoperative face of a grinding element comprising in combination a mainsupporting frame a pantograph linkage mechanism pivotally mounted onsaid frame and having parallel links of different lengths adjacentopposite ends thereof, an abrading tool of noncircular operative profilerigidly mounted on said smaller parallel link a stylus rigidly mountedon the longer parallel link of said pantograph and having an operativeface corresponding in profile to the operative face of the abrading toolbut on a larger scale corresponding to the ratio of the lengths of saidparallel links and a master pattern mounted on said frame and locatedadjacent said stylus.

8. In a machine of the class described a device for reconditioning theoperative face of a grinding element comprising in combination a mainsupporting frame a pantograph linkage mechanism having parallel links ofdifferent lengths adjacent opposite ends thereof and pivotally mountedon said frame, a diamond abrading tool of a shape following the naturalcleavage lines of the diamond structure rigidly mounted on the smallerof said parallel links a stylus rigidly mounted on the longer parallellink of said pantograph and having an operative face corresponding inprofile to the operative face of the abrading tool but on a larger scalecorresponding to the ratio of the lengths of said parallel links and amaster pattern mounted on said frame and located adjacent said stylus,said abrading tool and said stylus being mounted on said pantograph sothat the corresponding parts of the operative profiles of said tool andsaid stylus are parallel to one another.

9. In a machine of the class described, the coulbination of a grindingwheel, a pantograph pivotally supported and rectilinearly displaceablein opposite directions relatively to the grinding wheel, a diamondhaving a non-circular profile in its operative plane rigidly mounted onthe pantograph, a tracer bar forming an arm of the pantograph, a stylushaving a profile in its operative plane similar to that of the diamondbut on a larger scale and carried by said tracer bar, and a masterpattern engageable by the said stylus, the said diamond and stylus beingmounted with corresponding parts of their operative profiles in parallelrelationship to one another and always movable in the same plane.

10. In a machine of the class described, the combination of a grindingwheel, means to adjust the grinding wheel in opposite directions in itsown plane, means to adjust the grinding wheel in a plane at right anglesthereto, a diamond having an operative face of non-circular profile, astylus having an operative face corresponding in profile to theoperative face of the diamond but on a larger scale, a master patternadapted to coact with the stylus, and a pantograph rigidly carrying saiddiamond and said stylus and pivotally mounted on a frame disposedadjacent to the grinding wheel and adjustable in a plane parallel to theplane of the grinding wheel and also in a plane at right angles to thegrinding wheel, the point of support of the pantograph and the positionof the diamond and stylus carried thereby being so relatively arrangedthat the operative profiles or faces of the diamond and the stylus arealways maintained in parallel relationship during movement of the saidstylus over the master pattern.

11. In a machine of the class described, the combination of a grindingwheel, means to adjust the latter in its own plane, means to adjust thegrinding wheel in a plane at right angles thereto, a master pattern, aframe adjustable in opposite directions and in directions at rightangles thereto, a pantographic mechanism pivotally suspended on saidframe and carrying a non-rotatable and rigidly mounted diamond holder, adiamond having an operative face of non-circular profile and mounted anddisposed in said holder in a position such that a line passing throughany point on the operative edge of the diamond and the axis of the pivotadjacent to the pantographic suspension pivot forms the short arm of thepantographic mechanism, a stylus having an operative face similar inprofile to that of the diamond but on a larger scale and carried by thepantograph and in such manner that a line passing through a point on theoperative edge of the stylus corresponding to the corresponding pointon; the operative edge of the diamond and the axis of the pantographpivot remote from the f pantographic suspension pivot and alignedtherewith forms the long arm of the pantograph, andmeans to maintain theoperative profiles of the diamond and the stylus in parallelrelationship during movement of the said stylus over the master pattern.

12. In a machine of the class described, a pantographic appliancecomprising a main arm pivotally supported adjacent to a grinding wheel,a diamond of non-circular profile mounted in a holder which is pivotallyconnected to the pantograph main arm at a point near its pivotalsupport, a stylus of profile corresponding to that of the diamond but ona larger scale, an arm carrying the said stylus and pivotallyconnected-to the diamond holder relatively to that between the said mainsupport and the pivot of the stylus arm, as well as the distance betweenthe pivot of the diamond holder and a point on the operative face of thediamond relatively to that between the pivot of the stylus arm and acorresponding point on the operative face of thestylus being of the sameratio as the relative dimensions of the diamond and the stylus and thestraight line joining the pivot of the diamond holder and a point on theoperative face of the diamond and that joining the pivot of the stylusarm to a corresponding pivot on the operative fae being parallel to oneanother.

13. In a machine of the class described, a pantograph linkage mechanismcomprising a short arm, a long arm, a pivotal support for the short ofthe stylus.

, 5 arm, a pivotal support for the long arm, a diamond of non-circularprofile rigidly mounted at the extremity of the short arm, a stylushaving a profile corresponding to that of the diamond but on a largerscale and rigidly mounted at the extremity of the long arm, the distancebetween the pivotal support of the short arm and a point on;

the operative face of the diamond, relatively to the distance betweenthe pivotal support of the long arm and a corresponding point on theoperative face of the stylus being of the same ratio as the relativedimensions of the diamond and the stylus so that a straight line joiningthe pivot of the short arm to a point on the operative face of thediamond is parallel to a straight line joining the pivot of the long armto a corresponding point on the operative face of the stylus and ismaintained parallel thereto throughout the movement of the pantograph,

GERALD JOHN SU'I'I'ON.

